Well, (this may be wrong, but I'm about 90% sure) you'd attach a large alligator clip to a piece of wire that's reasonably long. Then attach that to a 200K 2W resistor, and attach that resistor to another large alligator clip. Wrap all the exposed metal in some insulation, and wawlaw!

It looks like they've got a drill bit in that picture, I suppose that could work as well.
Quote by kurtlives91
No poking no sticks...

seriously, i know very little about amps and moddin them, but i do know that what kurtlives said is a better option...my dad is an electrical engineer and his company still works with tubes on occasion and he has told me numerous times that this is what they do and whether i like it or not hes gonna do it to every tube amp i ever get....long story short, ^what he said.
Gibson SG Faded
Epi VJ Stack

Quote by Øttər
Whenever I clean my guitars, my family wonders why it smells so good; I say that I exude a fresh citrus scent from hidden orifices.
They stopped asking
Quote by kurtlives91
An much easier way it directly solder a 220K 3W resistor in parallel to your first cap. Just turn the amp off and it discharges itself.

No poking no sticks...

By first cap do you mean first cap in the power section? And you only need to do it on that one? (would this be C6 on a Valve Junior?)
If so, I'm all for not having to poke around every time I open that thing, which is often!

On amps with a standby switch, standby would need to be off (the setting you play with) for the caps to drain, correct?
Thanks, this is quite helpful information. I have another question though:
I have a 100µF/450V cap in parallel with C6, does that change anything?
I just use my multimeter... Both my amps are fully discharged within 5 minutes without any external touching, and they're a Laney VC30 and a V2 VJr combo.
The Laney Thread are big and clever. No exceptions.